大气科学学报2025，Vol.48Issue(6)：913-925,13.DOI:10.13878/j.cnki.dqkxxb.20250326001
北大西洋多年代际振荡对MJO环流周期特征年代际变化的影响
Impact of the Atlantic Multidecadal Oscillation on the interdecadal varia-bility of MJO periodicity
摘要
Abstract
The Madden-Julian Oscillation(MJO),the dominant mode of intraseasonal variability in the tropical atmosphere,is characterized by large-scale deep convection coupled with planetary-scale circulation.MJO events generally originate over the Indian Ocean and propagate eastward into the western Pacific.While the convective component weakens near the dateline,the circulation component continues eastward,completing a cycle within 30-90 days.Because of its strong influence on global weather and climate anomalies,understanding MJO varia-bility is essential for improving extended-range forecasts. MJO activity exhibits interdecadal variability in intensity,propagation speed,and spatial extent.Previous studies have primarily focused on intensity and propagation,while the period characteristics of MJO circulation and their interdecadal variations remain less well documented.Variability in MJO period length are is particularly relevant,as prolonged periods are associated with climate extremes such as southern China heatwaves,Meiyu rainfall in the Yangtze River basin,and Coastal Niño events. The Atlantic Multidecadal Oscillation(AMO)is a leading mode of interdecadal climate variability that mod-ulates ENSO,western Pacific tropical cyclones,and the Asian monsoon.Recent evidence suggests that AMO may influence MJO convective propagation by altering background winds and low-level moisture over the tropical Pacific.However,whether AMO also regulates the periodic characteristics of MJO circulation has not been sys-tematically examined. This study investigates the role of AMO in modulating the interdecadal variability of MJO circulation periods using ERA-20C reanalysis and ERSSTv5 sea surface temperature data.The analysis addresses three questions:1)whether AMO induces interdecadal variations in MJO circulation period characteristics,2)the physical processes responsible for these variations,and 3)the mechanism through which AMO exerts its influence. The results show that AMO significantly modulates MJO circulation periods.During positive AMO phases,the mean circulation period shortens to approximately 45 days,whereas during negative phases it lengthens to a-bout 60 days,with a correlation coefficient of-0.77.This variability is mainly associated with changes in propa-gation speed over the Western Hemisphere:accelerated propagation during positive phases results in shorter circu-lation periods,while decelerated propagation during negative phases produces longer periods.The modulation of propagation speed is linked to changes in the zonal sea surface temperature gradient between the tropical central-eastern Pacific and the tropical Atlantic.Positive AMO phases feature cold anomalies in the tropical central-eastern Pacific and warm anomalies in the tropical Atlantic,which enhance the zonal gradient and favor faster propagation. Although the circulation period varies with AMO phase,the convective period remains stable,with power spectra consistently peaking near 60 days within the 30-90-day band.This indicates that the coupling between MJO convection and circulation is modulated on interdecadal timescales. These findings demonstrate a trans-basin linkage between AMO and the interdecadal variability of MJO cir-culation periodicity,highlighting the role of AMO in regulating intraseasonal variability through large-scale ocean-atmosphere interactions.关键词
热带季节内振荡/大西洋多年代际振荡/年代际变化Key words
Madden-Julian Oscillation/Atlantic Multidecadal Oscillation/interdecadal variability引用本文复制引用
夏嘉诚,王璐,周旋,陈林..北大西洋多年代际振荡对MJO环流周期特征年代际变化的影响[J].大气科学学报,2025,48(6):913-925,13.基金项目
国家自然科学基金项目(42088101 （）
42576024) （）
江苏省自然科学基金优秀青年基金项目(BK20230061) （BK20230061）
